package ACWing.WeeklyRace;
//4794. 健身

import java.util.Scanner;

/**
 * @author :chenjie
 * @date :Created 2023/1/14 19:06
 */
public class Fitness {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        int max=0;
        int j=0;
        String[]arr={"chest","biceps","back"};
        int[]arr2=new int[3];
        for (int i = 0; i < n; i++) {
            int x=sc.nextInt();
            arr2[i%3]=arr2[i%3]+x;
            if(arr2[i%3]>max){
                max=arr2[i%3];
                j=i%3;
            }
        }
//        System.out.println(j);
        System.out.println(arr[j]);
    }
}
